Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w=map(int,input().split())
a=['*'*(w+2)]+['*'+input()+'*' for _ in range(h)]+['*'*(w+2)]
s=0
for i in range(1,h+1):
  s+=a[i].count('.')
from collections import deque
d=deque()
d.append([1,1])
c=[[10000]*w for _ in range(h)]
c[0][0]=1
di=[[0,1],[1,0],[-1,0],[0,-1]]
while d:
  g=d.popleft()
  for i in di:
    x=g[0]+i[0]
    y=g[1]+i[1]
    if a[x][y]=='.':
      if c[x-1][y-1]==10000:
        d.append([x,y])
        c[x-1][y-1]=c[g[0]-1][g[1]-1]+1
if c[h-1][w-1]==10000:
  print(-1)
else:
  print(s-c[h-1][w-1])